Genetic engineering has made it possible to produce large amounts of heterologous proteins or polypeptides in bacterial cells by means of recombinant expression systems. The expressed heterologous proteins may be mammalian, other eukaryo tic, viral, bacterial, cyanobacterial, archeabacterial or of synthetic origin.
The bacterial host cell of choice for expression of recombinant DNA has long been Escherichia coli. However, this microorganism has many disadvantages as a host cell including the inability to secrete recombinantly produced proteins, the precipitation of highly expressed recombinantly produced proteins into inclusion bodies within the cell, the inability to glycosylate recombinantly produced proteins and the difficulties faced when purifying a recombinantly produced protein from E. coli. 
The DNA sequences and methods for the expression of homologous and heterologous proteins in Flavobacterium heparinum, a Gram negative, non-pathogenic soil bacterium, have not been investigated. The ability to express heterologous and homologous polypeptides and proteins in F. heparinum would be desirable as the microorganism naturally produces glycosylated proteins. Thus, F. heparinum would be useful as a host cell for expression of recombinant DNA encoding mammalian proteins since they are often glycosylated. In addition, F. heparinum naturally produces low levels of the glycosaminoglycan degrading enzymes that act upon heparin and other glycosaminoglycans. The heparinase enzymes have significant medical utility and the production of these enzymes from their natural source would be desirable.
It is an object of the invention to provide nucleic acids and expression systems for the expression of recombinant DNA molecules in F. heparinum. Another object of the invention is to provide methods for use of F. heparinum as a host cell for the expression of recombinant DNA molecules.